Nitrogen trifluoride can be produced by the gas phase reaction of ammonia and fluorine. Reaction 1 illustrates the desired gas phase NF3 production reaction.3F2(g)+NH3(g)→NF3(g)+3HF(g)(ΔH =−904 KJ/g mole NF3)   Reaction 1
wherein (g) denotes the gas phase. A solid catalyst is often used to lower the required operating temperature, which increases the NF3 yield. However, it is very difficult to control the reactor temperature with this highly exothermic reaction. As a result, the gas phase ammonia and fluorine reaction produces substantial quantities of HF, N2, N2F2, and NH4F, with NF3 yields typically substantially less than ten percent.
U.S. Pat. No. 4,091,081 teaches a higher-yield process that produces nitrogen trifluoride [NF3] and by-product ammonium acid fluoride [NH4F(HF)x] by contacting a molten ammonium acid fluoride [NH4F(HF)x] with gaseous fluorine [F2] and ammonia [NH3]. U.S. Pat. No. 5,637,285 describes a similar process, wherein yield is further increased by utilizing a high level of mixing intensity and an ammonium acid fluoride having a HF/NH3 molar ratio greater than 2.55 (equivalent to a melt acidity x value of greater than 1.55). However, the process described in the '285 patent is undesirable for several reasons. The process disclosed in the '285 patent produces an ammonium acid fluoride waste stream, thereby creating disposal problems. Further, it is difficult to maintain the HF/NH3 molar ratio or x value of the bulk ammonium acid fluoride [NH4F(HF)x] at the desired level. There remains a need in the art for a high yield process for producing nitrogen trifluoride without the above-mentioned drawbacks.